a-Selective Ring-Opening Reactions of Bicyclo[1.1.0]butyl Boronic Ester with Nucleophiles
a-Selective Ring-Opening Reactions of Bicyclo[1.1.0]butyl Boronic Ester with Nucleophiles
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双环[1.1.0]丁基硼酯与亲核试剂的α-选择性开环反应
DOI：
10.1002/ange.202011739
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发表时间：
2020
影响因子：
--
通讯作者：
Guo L
中科院分区：
文献类型：
--
作者：
Guo L
研究了双环[1.1.0]丁基频哪醇硼酸酯（BCB-Bpin）与亲核试剂的反应。与带有吸电子基团（在 β 位与亲核试剂反应）的 BCB 不同，BCB-Bpin 仅在 α 位与多种以杂原子（O、S、N）为中心的亲核试剂发生反应。脂肪醇、酚、羧酸、硫醇和磺酰胺被发现是有效的亲核试剂，为制备α-杂原子取代的环丁基硼酸酯提供了方便的途径。相比之下，空间位阻双磺酰胺和相关亲核试剂与 BCB-Bpin 在 β' 位反应，生成具有高反式选择性的环丙烷。讨论了选择性的起源。
The reaction of bicyclo[1.1.0]butyl pinacol boronic ester (BCB‐Bpin) with nucleophiles has been studied. Unlike BCBs bearing electron‐withdrawing groups, which react with nucleophiles at the β‐position, BCB‐Bpin reacts with a diverse set of heteroatom (O, S, N)‐centred nucleophiles exclusively at the α‐position. Aliphatic alcohols, phenols, carboxylic acids, thiols and sulfonamides were found to be competent nucleophiles, providing ready access to α‐heteroatom‐substituted cyclobutyl boronic esters. In contrast, sterically hindered bis‐sulfonamides and related nucleophiles reacted with BCB‐Bpin at the β′‐position leading to cyclopropanes with high trans‐selectivity. The origin of selectivity is discussed.